6. DPDK Unit Testing Guidelines

This document outlines the guidelines for running and adding new tests to the in-tree DPDK test suites.

The DPDK test suite model is loosely based on the xUnit model, where tests are grouped into test suites, and suites are run by runners. For a basic overview, see the basic Wikipedia article on xUnit.

6.1. Background

The in-tree testing infrastructure for DPDK consists of multiple applications and support tools. The primary tools are the dpdk-test application, and the meson test infrastructure. These two are the primary ways through which a user will interact with the DPDK testing infrastructure.

There exists a bit of confusion with the test suite and test case separation with respect to dpdk-test and meson test. Both have a concept of test suite and test case. In both, the concept is similar. A test suite is a group of test cases, and a test case represents the steps needed to test a particular set of code. Where needed, they will be disambiguated by the word Meson to denote a Meson test suite / case.

6.2. Running a test

DPDK tests are run via the main test runner, the dpdk-test app. The dpdk-test app is a command-line interface that facilitates running various tests or test suites.

There are three modes of operation. The first mode is as an interactive command shell that allows launching specific test suites. This is the default operating mode of dpdk-test and can be done by:

$ ./build/app/test/dpdk-test --dpdk-options-here
EAL: Detected 4 lcore(s)
EAL: Detected 1 NUMA nodes
EAL: Static memory layout is selected, amount of reserved memory...
EAL: Multi-process socket /run/user/26934/dpdk/rte/mp_socket
EAL: Selected IOVA mode 'VA'
EAL: Probing VFIO support...
EAL: PCI device 0000:00:1f.6 on NUMA socket -1
EAL:   Invalid NUMA socket, default to 0
EAL:   probe driver: 8086:15d7 net_e1000_em
APP: HPET is not enabled, using TSC as default timer
RTE>>

At the prompt, simply type the name of the test suite you wish to run and it will execute.

The second form is useful for a scripting environment, and is used by the DPDK Meson build system. This mode is invoked by assigning a specific test suite name to the environment variable DPDK_TEST before invoking the dpdk-test command, such as:

$ DPDK_TEST=version_autotest ./build/app/test/dpdk-test --dpdk-options-here
EAL: Detected 4 lcore(s)
EAL: Detected 1 NUMA nodes
EAL: Static memory layout is selected, amount of reserved memory can be...
EAL: Multi-process socket /run/user/26934/dpdk/rte/mp_socket
EAL: Selected IOVA mode 'VA'
EAL: Probing VFIO support...
EAL: PCI device 0000:00:1f.6 on NUMA socket -1
EAL:   Invalid NUMA socket, default to 0
EAL:   probe driver: 8086:15d7 net_e1000_em
APP: HPET is not enabled, using TSC as default timer
RTE>>version_autotest
Version string: 'DPDK 20.02.0-rc0'
Test OK
RTE>>$

The above shows running a specific test case. On success, the return code will be ‘0’, otherwise it will be set to some error value (such as ‘255’, or a negative value).

The third form is an alternative to providing the test suite name in an environment variable. The unit test app can accept test suite names via command line arguments:

$ ./build/app/test/dpdk-test --dpdk-options-here version_autotest version_autotest
EAL: Detected 8 lcore(s)
EAL: Detected 1 NUMA nodes
EAL: Static memory layout is selected, amount of reserved memory can be...
EAL: Detected static linkage of DPDK
EAL: Multi-process socket /run/user/26934/dpdk/rte/mp_socket
EAL: Selected IOVA mode 'VA'
TELEMETRY: No legacy callbacks, legacy socket not created
APP: HPET is not enabled, using TSC as default timer
RTE>>version_autotest
Version string: 'DPDK 21.08.0-rc0'
Test OK
RTE>>version_autotest
Version string: 'DPDK 21.08.0-rc0'
Test OK
RTE>>

The primary benefit here is specifying multiple test names, which is not possible with the DPDK_TEST environment variable.

Additionally, it is possible to specify additional test parameters via the DPDK_TEST_PARAMS argument, in case some tests need additional configuration. This isn’t currently used in the Meson test suites.

6.3. Running test cases via Meson

In order to allow developers to quickly execute all the standard internal tests without needing to remember or look up each test suite name, the build system includes a standard way of executing the Meson test suites. After building via ninja, the meson test command with no arguments will execute the Meson test suites.

There are five pre-configured Meson test suites. The first is the fast test suite, which is the largest group of test cases. These are the bulk of the unit tests to validate functional blocks. The second is the perf tests. These test suites can take longer to run and do performance evaluations. The third is the driver test suite, which is mostly for special hardware related testing (such as cryptodev). The fourth suite is the debug suite. These tests mostly are used to dump system information. The last suite is the extra suite for tests having some known issues.

The Meson test suites can be selected by adding the --suite option to the meson test command. Ex: meson test --suite fast-tests:

$ meson test -C build --suite fast-tests
ninja: Entering directory `/home/aconole/git/dpdk/build'
[2543/2543] Linking target app/test/dpdk-test.
1/60 DPDK:fast-tests / acl_autotest          OK       3.17 s
2/60 DPDK:fast-tests / bitops_autotest       OK       0.22 s
3/60 DPDK:fast-tests / byteorder_autotest    OK       0.22 s
4/60 DPDK:fast-tests / cmdline_autotest      OK       0.28 s
5/60 DPDK:fast-tests / common_autotest       OK       0.57 s
6/60 DPDK:fast-tests / cpuflags_autotest     OK       0.27 s
...

The meson test command can also execute individual Meson test cases via the command line by adding the test names as an argument:

$ meson test -C build version_autotest
ninja: Entering directory `/home/aconole/git/dpdk/build'
[2543/2543] Linking target app/test/dpdk-test.
1/1 DPDK:fast-tests / version_autotest OK             0.17s
...

Note that these test cases must be known to Meson for the meson test command to run them. Simply adding a new test to the dpdk-test application isn’t enough. See the section Adding a suite or test case to Meson for more details.

6.4. Adding tests to dpdk-test application

Unit tests should be added to the system whenever we introduce new functionality to DPDK, as well as whenever a bug is resolved. This helps the DPDK project to catch regressions as they are introduced.

The DPDK test application supports two layers of tests:

  1. test cases which are individual tests

  2. test suites which are groups of test cases

To add a new test suite to the DPDK test application, create a new test file for that suite (ex: see app/test/test_version.c for the version_autotest test suite). There are two important functions for interacting with the test harness:

REGISTER_TEST_COMMAND(command_name, function_to_execute)

Registers a test command with the name command_name and which runs the function function_to_execute when command_name is invoked.

unit_test_suite_runner(struct unit_test_suite *)

Returns a runner for a full test suite object, which contains a test suite name, setup, tear down, a pointer to a list of sub-testsuites, and vector of unit test cases.

Each test suite has a setup and tear down function that runs at the beginning and end of the test suite execution. Each unit test has a similar function for test case setup and tear down.

Each test suite may use a nested list of sub-testsuites, which are iterated by the unit_test_suite_runner. This support allows for better granularity when designing test suites. The sub-testsuites list can also be used in parallel with the vector of test cases, in this case the test cases will be run, and then each sub-testsuite is executed. To see an example of a test suite using sub-testsuites, see app/test/test_cryptodev.c.

Test cases are added to the .unit_test_cases element of the appropriate unit test suite structure. An example of both a test suite and a case:

 1#include <time.h>
 2
 3#include <rte_common.h>
 4#include <rte_cycles.h>
 5#include <rte_hexdump.h>
 6#include <rte_random.h>
 7
 8#include "test.h"
 9
10static int testsuite_setup(void) { return TEST_SUCCESS; }
11static void testsuite_teardown(void) { }
12
13static int ut_setup(void) { return TEST_SUCCESS; }
14static void ut_teardown(void) { }
15
16static int test_case_first(void) { return TEST_SUCCESS; }
17
18static struct unit_test_suite example_testsuite = {
19       .suite_name = "EXAMPLE TEST SUITE",
20       .setup = testsuite_setup,
21       .teardown = testsuite_teardown,
22       .unit_test_cases = {
23            TEST_CASE_ST(ut_setup, ut_teardown, test_case_first),
24
25            TEST_CASES_END(), /**< NULL terminate unit test array */
26       },
27};
28
29static int example_tests()
30{
31    return unit_test_suite_runner(&example_testsuite);
32}
33
34REGISTER_TEST_COMMAND(example_autotest, example_tests);

The above code block is a small example that can be used to create a complete test suite with test case.

Sub-testsuites can be added to the .unit_test_suites element of the unit test suite structure, for example:

 1static int testsuite_setup(void) { return TEST_SUCCESS; }
 2static void testsuite_teardown(void) { }
 3
 4static int ut_setup(void) { return TEST_SUCCESS; }
 5static void ut_teardown(void) { }
 6
 7static int test_case_first(void) { return TEST_SUCCESS; }
 8
 9static struct unit_test_suite example_parent_testsuite = {
10       .suite_name = "EXAMPLE PARENT TEST SUITE",
11       .setup = testsuite_setup,
12       .teardown = testsuite_teardown,
13       .unit_test_cases = {TEST_CASES_END()}
14};
15
16static int sub_testsuite_setup(void) { return TEST_SUCCESS; }
17static void sub_testsuite_teardown(void) { }
18
19static struct unit_test_suite example_sub_testsuite = {
20       .suite_name = "EXAMPLE SUB TEST SUITE",
21       .setup = sub_testsuite_setup,
22       .teardown = sub_testsuite_teardown,
23       .unit_test_cases = {
24            TEST_CASE_ST(ut_setup, ut_teardown, test_case_first),
25
26            TEST_CASES_END(), /**< NULL terminate unit test array */
27       },
28};
29
30static struct unit_test_suite end_testsuite = {
31       .suite_name = NULL,
32       .setup = NULL,
33       .teardown = NULL,
34       .unit_test_suites = NULL
35};
36
37static int example_tests()
38{
39    uint8_t ret, i = 0;
40    struct unit_test_suite *sub_suites[] = {
41           &example_sub_testsuite,
42           &end_testsuite /**< NULL test suite to indicate end of list */
43     };
44
45    example_parent_testsuite.unit_test_suites =
46            malloc(sizeof(struct unit_test_suite *) * RTE_DIM(sub_suites));
47
48    for (i = 0; i < RTE_DIM(sub_suites); i++)
49        example_parent_testsuite.unit_test_suites[i] = sub_suites[i];
50
51    ret = unit_test_suite_runner(&example_parent_testsuite);
52    free(example_parent_testsuite.unit_test_suites);
53
54    return ret;
55}
56
57REGISTER_TEST_COMMAND(example_autotest, example_tests);

6.5. Designing a test

Test cases have multiple ways of indicating an error has occurred, in order to reflect failure state back to the runner. Using the various methods of indicating errors can assist in not only validating the requisite functionality is working, but also to help debug when a change in environment or code has caused things to go wrong.

The first way to indicate a generic error is by returning a test result failure, using the TEST_FAILED error code. This is the most basic way of indicating that an error has occurred in a test routine. It isn’t very informative to the user, so it should really be used in cases where the test has catastrophically failed.

The preferred method of indicating an error is via the RTE_TEST_ASSERT family of macros, which will immediately return TEST_FAILED error condition, but will also log details about the failure. The basic form is:

RTE_TEST_ASSERT(cond, msg, ...)

In the above macro, cond is the condition to evaluate to true. Any generic condition can go here. The msg parameter will be a message to display if cond evaluates to false. Some specialized macros already exist. See lib/librte_eal/include/rte_test.h for a list of defined test assertions.

Sometimes it is important to indicate that a test needs to be skipped, either because the environment isn’t able to support running the test, or because some requisite functionality isn’t available. The test suite supports returning a result of TEST_SKIPPED during test case setup, or during test case execution to indicate that the preconditions of the test aren’t available. Example:

$ meson test -C build --suite fast-tests
ninja: Entering directory `/home/aconole/git/dpdk/build
[2543/2543] Linking target app/test/dpdk-test.
1/60 DPDK:fast-tests / acl_autotest          OK       3.17 s
2/60 DPDK:fast-tests / bitops_autotest       OK       0.22 s
3/60 DPDK:fast-tests / byteorder_autotest    OK       0.22 s
...
46/60 DPDK:fast-tests / ipsec_autotest       SKIP     0.22 s
...

6.6. Checking code coverage

The Meson build system supports generating a code coverage report via the -Db_coverage=true option, in conjunction with a package like lcov, to generate an HTML code coverage report. Example:

$ meson setup build -Db_coverage=true
$ meson test -C build --suite fast-tests
$ ninja coverage-html -C build

The above will generate an HTML report in the build/meson-logs/coveragereport/ directory that can be explored for detailed code covered information. This can be used to assist in test development.

6.7. Adding a suite or test case to Meson

Adding to one of the Meson test suites involves editing the appropriate Meson build file app/test/meson.build and adding the command to the correct test suite class. Once added, the new test will be run as part of the appropriate class (fast, perf, driver, etc.).

A user or developer can confirm that a test is known to Meson by using the --list option:

$ meson test -C build --list
DPDK:fast-tests / acl_autotest
DPDK:fast-tests / bitops_autotest
...

Some of these test suites are run during continuous integration tests, making regression checking automatic for new patches submitted to the project.

In general, when a test is added to the dpdk-test application, it probably should be added to a Meson test suite, but the choice is left to maintainers and individual developers. Preference is to add tests to the Meson test suites.

6.8. Running cryptodev tests

When running cryptodev tests, the user must create any required virtual device via EAL arguments, as this is not automatically done by the test:

$ ./build/app/test/dpdk-test --vdev crypto_aesni_mb
$ meson test -C build --suite driver-tests \
             --test-args="--vdev crypto_aesni_mb"

Note

The cryptodev_scheduler_autotest is the only exception to this. This vdev will be created automatically by the test app, as it requires a more complex setup than other vdevs.